Ink jet printers utilize print cartridges having printheads for directing ink droplets onto a medium, such as paper, in patterns corresponding to the indicia to be printed on the paper. In general, ink is directed from a reservoir via flow paths to ink chambers and associated orifices or nozzles for release onto the paper. Heaters or other energy imparting devices are provided adjacent the nozzles for energizing the ink in the ink chambers in order to propel droplets of ink through the nozzle holes to provide a dot of ink on the paper. During a printing operation the print head is moved relative to the paper and ink droplets are released in patterns corresponding to the indicia to be printed by electronically controlling the energy imparting devices to selectively propel ink through only those nozzles for a given position of the printhead relative to the paper.
Printheads typically include a nozzle plate attached, as by adhesive, to a silicon chip containing the energy imparting devices. Electrical connections are provided to the chip to connect the energy imparting devices on the chip with the printer controller, usually be means of a flex circuit. A flex circuit is a plastic or polymeric tape containing electrical traces which are electrically connected to contact pads. The contact pads correspond to contact pads on the printer carriage and provide electrical continuity between the chip and the printer controller.
As the speed and print quality of ink jet printers increases, the number of nozzle holes and energy imparting devices on the printhead likewise increases. Increasing the size of the printheads or nozzle plates is not practical because the production yield of semiconductor chips decreases dramatically as the size of the chip increases. Accordingly, this requires closer spacing of the energy imparting devices for a given chip size.
Higher quality printing also requires that the ink droplets be ejected so they impact the printed media in a precise location. In order to reduce drop placement variability, it is preferred to space the printhead device closer to the print media. However, due to variability in the smoothness or planarity of the printheads themselves, printheads are required to be spaced a minimum distance from the print media in order to reduce or eliminate wear of the printhead caused by the print media rubbing against the printhead during printing.
Accordingly it is an object of the present invention to provide an improved method for manufacturing ink jet printheads.
Another object of the present invention is to provide a method of the character described which enables the production of printheads having greater reliability and performance characteristics as compared to printheads provided using conventional techniques.
A further object of the present invention is to provide a method for manufacturing a printhead having a greater clearance tolerance between the nozzle plate and print media than conventional printheads.